Various propulsion systems are known to propel marine vessels. Examples of those propulsion systems are retractable fixed thruster assemblies and retractable azimuth thruster assemblies. Retractable fixed thrusters are not rotatable, whereas retractable azimuth thrusters are rotatable in any horizontal direction.
Regarding the configuration of the drive train for the retractable thruster, Z-drive configurations and L-drive configurations are distinguished. In a Z-drive configuration, the power transmission has two right angle turns, thus resembling the letter “Z”. This name is used to differentiate the arrangement of drive to that of the L-drive. In power transmissions with L-drive configuration, the rotary motion has to make one right angle turn, thus looking like the letter “L”. Generally, Z-drive configurations are commonly equipped with combustion engines, for example, diesel fuel engines and gaseous fuel engines, as power source for the propeller. In contrast, L-drive configurations are often provided with electric motors as prime movers.
For example, retractable thruster assemblies for marine vessels are known from WO 2012/089914 A1 and WO 2011/031158 A2.
The present disclosure is directed, at least in part, to improving or overcoming one or more aspects of prior systems.